While not limited thereto, the present invention is particularly adapted for use with an atmospheric sampling pump used in coal mines and other areas of high-dust content. In a sampling pump arrangement of this type, dust-laden air is drawn through a disc filter, the filter being weighed before and after a predetermined time interval (usually 8 hours) to determine the amount of dust which has been collected and, hence, the dust content of the surrounding atmosphere. In order to obtain an accurate indication of dust concentration, however, it is necessary to utilize a pump which draws air through the filter at a constant mass flow rate. This is accomplished with the use of a mass flow sensor which electronically monitors mass flow and compares it to a set-point value. The pump is then controlled in a manner that will minimize the difference between the measured flow and the set-point value. The mass flow regulation is automatically maintained until the compliance range of the pump is exceeded (i.e., excessive pneumatic loading).